Re: [Gen-art] Gen-Art review of draft-ietf-core-block-19

[Jouni Korhonen <[e-mail]>]

Hi Jouni,

Just saying.. the use of NUM was not crystal clear just by reading the 
draft and not having the followed the core block development & 
discussion past few years.

Thanks,	
	Jouni

4/27/2016, 2:33 PM, Carsten Bormann kirjoitti:
> Hi Jouni,
>
>>>> * The intoduction mentions that the block transfwer can be used for
>>>> random access. This is not separately described anywhere in the
>>>> documents. Although the operation is more or less trivial I would
>>>> appreciate an example or some text there because the Block2 overloads
>>>> the NUM value 0 with special meaning (for the cases where the first ever
>>>> accessed block is not the block number 0).
>>>
>>> The random access operation is not described in this draft, but it is
>>> indeed quite obvious how one would make use of such a capability.
>>> Its use would require some previous understanding between client and
>>> server (possibly gained by the client simply trying out random access).
>>> I'm not sure how NUM=0 is special in this case.
>>
>> NUM=0 is used in some cases to indicate the desired block size in the
>> initial request (as I read and understand from the draft.. if that is
>> not the case then it needs to stated more clearly that it is not the
>> case). I mean the text in 2.4 and 2.8 for example.
>
> There is definitely a special case for NUM=0 in 2.8 (multicast), but
> that is because, for discovery, the client will switch to unicast for
> all other blocks.  It doesn't sound reasonable to "discover" a resource
> while performing random access to it.
>
> The text in 2.4 is more about the outcome of using Block2 options
> properly; here we prefer the wording "first request"/"first response"
> because indeed that might be for a block with NUM≠0.
>
> (The special case for NUM≠0 in the last paragraph of 2.10 is about not
> creating "holes".)
>
> Grüße, Carsten
>